Heaviest bullet for mag length 5.56 Nato

[TiGuy]

I have an 8 twist AR and need advice on the heaviest bullet I can load to 2.260 COAL. Seems like some 77 grain rounds might work. I am looking for a long range target round (600 yd) and I only use ball powder such as 748 or H335 so I can drop charge. Any guidance?

 

[swehrman]

77 grain is the heaviest that I know of. I've seen some loading data for 77's using WW748, but most people use RL15, Varget, N140. If I remember correctly 748 has a reputation for being temperature sensitive and so loads worked up in cooler weather will get squirrely when it gets warm.

-- Scott

 

[GerryM]

Reloader 15 is kind of coarse to drop from a measure.
I think you will have better luck with the VV`140 and varget,
They should drop from a measure fairly easy.

 

[280man]

Most service rifle shooters that I know don't worry about mag length for the 600 yard line because its slow fire single load. If you have to have them fit in a mag I would stick with 69gr match or 75gr AMAX

 

[kentuckytroutbum]

My favorite load for the 600 yd HP line is a Hornady 75 gr. Amax on top of Accurate A 2520, seated 0.020" off the lands. 2520 doesn't seem to be temp sensitive, as I've shot this load on a 95 deg. sunny & humid day without any pressure signs. The load is longer than the magazine, so it is single loaded.

Bill

 

[people]

Lol good times.

I have used many different powders to see if I can get these to shoot any better. Many different powders work but I do not remember right off the top of my head what ones I have tried.

 

[Klong]

Do not like the 75 AMAX for mag length ammo. The 75 AMAX ogive puts the bullet so far into the case neck that the neck is not gripping the bullet. You can use the Hornady 75 HPBT though. The 73 Berger works best for me with V540 powder. The standard load for many is 24.7 varget and the 77 SMK. Start 10 % lower and work up.

 

[cmillard]

klong, 24.7 seems a little high for the 77. i loaded some 77 sierras a few years back in my NATO chambered M4 that I built and 24.5 grains of varget smoked the primers. it also stretched the primer pockets too much to where the brass was not loadable again. i knocked the charge back a bit--24.0 i think and that worked much better

 

[Klong]

cmillard, that is why I said start low and work up. My chambers are Wylde design and may account for the ability to shoot hotter loads. I only get about 6 loading before primers start to loosen up.

Every rifle is a little different, but I know dozens of competitive shooters that shoot this load and I have shot it in at least 4 of my rifles.

 

[cmillard]

Klong, are you running a carrier weight with that load? i shot a carrier weight (tungsten insert) along with an enidine hydro buffer in the stock and it still smoked the primers. that was with 2 different barrels. i was suprised to see that it still did it even in the NATO chamber. but, i think it could have been because of the CCI BR-4 primers--they tend to be hot. i have not tried my go to primers (wolf srm) with that load though.

 

[Klong]

No carrier weights and I shot BR4's and 450 primers without problems. The load I listed is a common load used for highpower rifle competition and the standard load used by many competitors at the National Matches (DCM) for Infantry Man's team matches (AKA Rattle battle).

 

[cmillard]

it must have been my barrels then. i was using sorted Lake City brass--the cases with the biggest internal volume--and the primers still blanked. once again, all barrels are different--as are powder lots and primer lots!!

 

[762willdo]

You can go with the 77SMK if you want its a good bullet but if you look at the numbers on the berger 70 you will be suprised, its all i shoot now.

 

[15Tango]

In regard to mag loaded length I've never really noticed the Berger 70 grain before - 371 BC isn't bad at all. Seems like the 69 SMK gets a lot of attention but the BC is only .301. I made the switch from 69 SMKs to Hornady 68 HPBT match last year which has a BC of .355 and they're only $14.73 per 100 from Powder Valley. The Berger looks good with a bit better BC but they cost nearly double.

I'm bringing some 68 Hornady BTHPs down to Texas (along with a lot of other rifles) at the end of the month for hog hunting, if I end up shooting anything with them I'll take some pictures and give a little report.

If you're going for all out weight for lethality in hunting it might be hard to beat the 77 SMK though. I've heard nothing but good about their use over in Afghanistan.

Wayne